ACROCENTRIC CHROMOSOME ASSOCIATIONS IN MAN

Abstract

Heterogeneity among chromosomes was a highly significant source of variation for association proportions, while culture, slide and observer were negligible sources of variation for association proportions although important for numbers of associations. The consequences of these results for tests of group differences were discussed. Each pair of acrocentric chromosomes had its own characteristic probability of entering into association. This was presumably a combination of the probability for each individual member of the pair, a proposition easily tested utilizing acrocentric chromosomes carrying polymorphisms which allowed each member of the pair to be individually recognized. A mathematical theory for pairwise satellite association was developed and shown to fit observations on banded chromosomes. While very significant heterogeneity was found among individuals in the frequency with which different chromosomes entered into associations, there was no significant evidence for preferential association between any particular chromosomes, either heterologous or homologous. This finding of apparently random associations between different chromosomes was contrary to claims made by other investigators and should be tested on material. No correlation was found between the phenotype of the chromosome, as judged by cytogenetic polymorphisms, and its probability of association.